Tree Pest & Disease Guide

29 major threats to trees across the United States. Identify pests, understand the damage, and know what to do. Sorted by severity.

Critical Threats (8)

Asian Longhorned Beetle

Maples (primary), birch, elm, willow, horse chestnut, ash

Critical Insect Pest 1 region

Citrus Greening

All citrus species - orange, grapefruit, lemon, lime

Critical Disease 1 region

Emerald Ash Borer

All ash species (Fraxinus) - green, white, black, blue ash

Critical Insect Pest 2 regions

Formosan Subterranean Termites

Both dead wood and living trees - will hollow out live oaks and other species from the inside

Critical Insect Pest 1 region

Laurel Wilt

Redbay, sassafras, swamp bay, avocado, pondspice

Critical Disease 1 region

Mountain Pine Beetle

Lodgepole pine (primary), ponderosa pine, limber pine, whitebark pine

Critical Insect Pest 1 region

Rapid Ohia Death

Ohia Lehua (Metrosideros polymorpha) - the most important native forest tree in Hawaii

Critical Pest/Disease 1 region

Sudden Oak Death

Tanoak (most lethal), coast live oak, California black oak, Shreve oak, and 100+ other species as carriers

Critical Disease 1 region

High Threats (18)

Bark Beetle Complex

Ponderosa pine, pinyon pine, and other conifers at higher elevations

High Insect Pest 1 region

Beech Leaf Disease

American Beech and European Beech

High Disease 1 region

Citrus Pest Complex

All citrus - residential citrus trees throughout urban Southern California

High Disease 1 region

Coconut Rhinoceros Beetle

Coconut palm (primary), other palms, potentially other plants

High Insect Pest 1 region

Cytospora Canker

Blue spruce, aspen, cottonwood

High Disease 1 region

Drought/Bark Beetle Complex

Pines, firs, cedars - primarily in mountain/foothill areas

High Insect Pest 1 region

Erythrina Gall Wasp

Erythrina species - wiliwili (native), coral trees (ornamental)

High Insect Pest 1 region

Goldspotted Oak Borer

Coast live oak, California black oak, canyon live oak

High Insect Pest 1 region

Hemlock Woolly Adelgid

Eastern Hemlock and Carolina Hemlock

High Insect Pest 1 region

Invasive Shot Hole Borers

100+ species - sycamores, box elder, coast live oak, avocado, willows, maples most affected

High Disease 1 region

Ips Beetle Complex

Spruce, pine - urban and forest settings

High Insect Pest 1 region

Laminated Root Rot

Douglas fir (primary), grand fir, mountain hemlock - the dominant conifers of the PNW

High Disease 1 region

Lethal Bronzing

Multiple palm species - Phoenix (date palms), Sabal palmetto, coconut palm, and others

High Disease 1 region

Oak Wilt

Red oak group (red, pin, scarlet, black - usually fatal). White oak group (white, bur, swamp white - slower, sometim...

High Disease 1 region

Southern Pine Beetle

Loblolly, shortleaf, Virginia, pitch, and other southern pines

High Insect Pest 1 region

Spotted Lanternfly

Tree of Heaven (primary host), but feeds on 70+ species including maples, oaks, walnut, willow, birch, grape

High Disease 1 region

Swiss Needle Cast

Douglas fir - the most common tree in PNW landscapes

High Disease 1 region

Texas Root Rot

Over 2,000 plant species - most susceptible: shade trees, fruit trees, ornamentals in alkaline soil

High Disease 1 region

Moderate Threats (3)

Bronze Birch Borer

European white birch (highly susceptible), paper birch, other birch species

Moderate Insect Pest 1 region

Giant Whitefly

Ornamental trees and shrubs - hibiscus, ficus, mulberry, citrus

Moderate Insect Pest 1 region

Palo Verde Root Borer

Palo Verde trees (primary), but larvae found in roots of other desert trees

Moderate Insect Pest 1 region